Compare last to second last record for each contract - sql

Question

To keep it simple, my question is similar to THIS QUESTION, PART 2, only problem is, I am not running Oracle and thus can not use the rownumbers.
For those who need more information and examples:
I have a table
contractId date value
1 09/02/2011 A
1 13/02/2011 C
2 02/02/2011 D
2 08/02/2011 A
2 12/02/2011 C
3 22/01/2011 C
3 30/01/2011 B
3 12/02/2011 D
3 21/01/2011 A
EDIT: added another line for ContractID. Since I had some code myself, but that would display the following:
contractId date value value_old
1 09/02/2011 A
2 08/02/2011 A D
3 30/01/2011 B C
3 30/01/2011 B A
But that is not what I want ! The result should still be as below!
Now I want to select the last record before a given date and compare that with the previous value.
Suppose the 'given date' is 11/02/2011 in this example, the output should be like this:
contractId date value value_old
1 09/02/2011 A
2 08/02/2011 A D
3 30/01/2011 B C
I do have the query to select the last record before the given date. That is the easy part. But to select the last record before that, I am lost...
I really hope I can get some help here, have been breaking my head over this for days and looking for answers on the web and stackoverflow.

Answer 1

One possibility:
SELECT a.contractId, a.Date, a.Value, (SELECT Top 1 b.[Value]
FROM tbl b
WHERE b.[Date] < a.[Date] And b.ContractID=a.ContractID
ORDER BY b.[Date] Desc) AS Old_Value
FROM tbl AS a
WHERE a.Date IN
(SELECT TOP 1 b.Date
FROM tbl b
WHERE b.ContractID=a.ContractID
AND b.Date < #2011/02/11#
ORDER BY b.date DESC)

Answer 2

As promised, I would also post my answer. Although at this point, I still think Remou's answer is better, since the code is shorter and it seems more efficient (calls the same table fewer times). But here goes:
Query1:
SELECT c.contractID, c.firstofdates, a.value, d.value, d.date
FROM (table1 AS A RIGHT JOIN (SELECT b.cid,max(b.date) AS FirstOfdates
FROM table1 as B
where b.date < #02/11/2011#
GROUP BY b.contractID ) AS c ON (a.date = c.firstofdates) AND (a.contractID = c.contractID))
LEFT JOIN (select e.contractID, e.date, e.value
from table1 as e
) AS d ON (d.date < c.firstofdates) AND (d.contractID = c.contractID);
This query actually gives the result with the extra row for the 3rd contractID.
Query2:
SELECT b.contractID, max(a.date) AS olddate
FROM table1 AS a RIGHT JOIN (select contractID, firstofdates
from Query1) AS b ON (a.contractID= b.contractID) AND (a.date < b.firstofdates)
GROUP BY b.contractID;
And then to combine both:
Query3:
SELECT Query1.contractID, Query1.firstofdates AS [date], Query1.A.value AS [value], Query1.d.value AS [old value]
FROM Query1 RIGHT JOIN Query2
ON (Query1.date=Query2.olddate or Query2.olddate is null) AND (Query1.cid = Query2.cid);